Valve-gear.



Patented July 4, I899.

c M H A w n .W? A n n 3 d v .1. M c N M WM .b Pr 8 W .0.

J. A. SEYMOUR.

VALVE GEAR.

(Application filed July 27, 1897. Renewed May 25, 1899.)

(No Model.)

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El Ic" Witnesses UNITED STATES PATENT OFFICE;

JAMES ALWABD SEYMOUR, OF AUBURN, NEW YORK.

VA LVE-GEAUR.

Application filed I'ebruary27, 1 897. Renewed May 25,1899. Eierial No. 718,194. (No model.)

I To aZZ whom, it may concern:

Be it known that I, JAMES ALWARD SE'Y MOUR, of the city of Auburn, State of New York, have invented'certain new and useful Improvements in Valve-Gear for Steam-En gines, of which the following is a description,

reference being had to the accompanying drawing, forming part of this specification.

My invention relates to the valves andoperating mechanism by which the admission and cut-off of steam to the cylinders of steamengines are controlled; and'it consists incertain novel arrangements and combinations of the valve-actuating mechanisms whereby the regular movement imparted to the valves by their actuating devices is, by means of connecting devicesinterposed between said actuating devices and said valves, made irregular, and the speed of said valves varies at different points of their travel, being quickened at times and then retarded, so that the valves are made to pause at one end of their stroke and a dwell or diminution of speed occurs.

Theobject of the variation of the speed or movement above referredto is to diminish the travel of the valves after they are closed, or, in other words, to give the valves such travel as shall be necessary to secure adequate port-opening and a suflicient seal when closed, and to suppress, further, unnecessary valve motion, which usually takes place after 'closing'of the valve and when an unbalanced valve is under considerable steam-pressure, producing proportionate friction. i

It will'be evident that the pause above referred to may be accomplished by various forms of connecting mechanisms. In fact, any form of connecting mechanism in which a member to which is imparted a rocking or pendulum motion serves to actuatea succeeding member having a rocking or reciprocating sliding movement interposed between the valve and its actuating-eccentric will accomplish this result it properly positioned and timed relative to one another. A

The drawing forming part of this specification is intended simply to illustrate one form of mechanism by which theabove-described function may be accomplished.

The pause above described is of particular value as applied to multiported or gridiron valves, becausein' such valves, each grid be ing functionally a separate valve, if the eccentric motion be unvaried and be transmitted directly'tothe valve without the ,intervention of some accelerating'or retarding mechanism the valve travel will be so much increased that'in order to prevent each grid from interfering with the functions of its adjacent grid it would be necessary to space them-so far apart as to cause a great length of v alve,which,with therequisite corresponding length of steam-chest and port, would involve an inconvenient, if-not an impracticable, construction and result in an undesirable waste of steam from t e necessarily large clearance-space. These ifficultieshaveheretofore been avoided by the use of a releasing type of valve-gear with asingle valve for both admission and cut-ofi? of steam instead of the preferable positively-driven type of valve.

It is intended hereby to limit the scope of thisinvention to the combination, with multiported or gridiron valves situated at each end, respectively, of the cylinder, each being actuated by a fixed eccentric, which valves ef feet the admission of steam to the cylinder at the proper time, of similar multiported or gridiron valves superimposed thereupon and serving as cut-off valves, being actuated by an eccentric, the position of which with reference to the crank is variable and under control of the governor and the interposed valvecontrolling and speed-varying mechanism, which produce thedwell or diminution of speed-at certainpoints of the travel of both said main and cut-off valves, as hereinbefore described. As the valve-gear which forms the subject-matter of the present invention is well adapted for use in connection with the type of valve shown, it is capableot' use with other forms of steam-valves.

Referring to the drawing, a rocking-shaft G, moving with regular rocking or oscillating motion imparted by an eccentric or crank, is provided with the rocker-arm H, connecting through pin A and link I to a pin A, passing through the radius-bar J and link U, the latter operating through pin Y upon the slide K, attached to the main valve M by the valverod L. The regularinovement du'e to the eccentric of the rock -shaft G above mentioned is represented by the extreme positions of the center of the pin Aviz., a and cand the center of this travel is represented by the point 1). The corresponding positions of the center of pin A are represented by points a b a, corresponding to points a b 0, respectively, above mentioned. It will be noted that both a and c are equally distant from b, but that b is situated nearer to 0 than to a. The irregular motion communicated to the valve M through link U, slide K, and rod L is still further increased, so that a" b" 0 represent various positions of a single point on the valve M and correspond to positions a b 0 above mentioned, position I) being very much nearer to 0 than to a.

It will be noted that the irregularity'or change of the movement of the valve M is accomplished by two stages, which enablesa longer pause'motion or diminution of movement to be effected at eudof stroke of valve,

but which is not essential to securing sub stantially the advantages of the invention which can be secured by a single-stage distortion. In a similar manner the rock-shaft N receives a regularrocking movement from the governor-eccentric. The travel of the center of the pin D in rocker-arm V, situated upon this rock-shaft N, is represented by the lined cf, the extreme points of travel being represented by d andfand the center point by e, this motion beingcommunicated through the link 0 and pin D to the bell-crank P, pivoted at Q. The positions of the centers of the pin D, connecting said link 0 and bellcrank P, will be represented by d e f, corresponding to movementd cf above mentioned, the motion being from this point transmitted Without further variation through bell-crank P, the pin D", the link R, the pin X, and the valve-rod S to the cnt-oif valve T, the positions of asingle point upon the latter corresponding to d ef being 61' cf, the point e being nearer to f than to 01, whereas in the original motion d ef, e is equally distant from d andf.

It will be noted in the drawing that the irregularity is carried to such an extent that 0 moves past the position at which center lines of the toggle-joint mechanism formed by the radius-link J and link U are in a straight line. This causes a slight return movement of the valve at one end of the stroke, after which it returns to the extreme position 10 before making the main stroke, so that the point 0 although corresponding to the extreme point of travel of the eccentric is not at the extreme position of the valve. 0, in fact, is farther from it than the point I) and falls between I)" and a. It will be apparent that by thus forcing the said togglejoint past its center the length of the dwell of the valve is materiallyincreased,although the state of actual rest of the Valve is but momentary, as it is making its forward and return movement due to the toggle joint passing its center before it starts on its return port-opening stroke, so that all danger of the valve sticking by reason of remaining too long at rest is removed.

It should be observed that it is not necessary to vary and change the motion of the eccentric sufficiently to fully obtain the conditions above described, since very substantial benefits will accrue when only a slight variation in the motion of said eccentric occurs.

From the foregoing it will be seen that the valves reach their maxim um rapidity of movement during the first part of the stroke of the rocker-arms on the rock-shafts and that the dwell 0r diminution of speed occurs during the latter half of said stroke, or when the valve is at the end of its travel, so that unnecessary movement of the valve is done away with.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The combination with a multiported or gridiron main valve for each end of the cylinder, of multiported or gridiron auxiliaryor cut-off valves superimposed upon said main valves, actuating fixed main and governorcontrolled auxiliary eccentrics for said valves, mechanism for connecting each of said valves with its eccentric comprising a rock-shaft provided with a rocker-arm, a' radius-bar pivoted on the frame of the engine, a link connecting the said radius-bar with the valve- -rod, and a link connecting said rocker-arm with said radius-bar, so as that the maximum rapidity of movement of the valve is reached duringthat portion of stroke when it is opening and closing the ports and a diminution of speed is given at the other end of the move ment of said valve.

2. The combination with a multiported or gridiron main valve for each end of the cylinder, of multiported or gridiron auxiliary or cut-off valves superimposed upon said main valves, actuating fixed main and governorcontrolled auxiliary eccentrics for said valves, mechanism for connecting each of said'valves with its eccentric eomprisinga rock-shaft provided with a rocker-arm, a radius-bar, connections between said radius-bar and the valve-rod, and a link connecting said rockerarm and radins-bar,the said rocker-arm and radius-bar being so positioned and timed relative to each other that the travel of the rockerarm during the first part of its stroke imparts a maximum rapidity of movement to the radius-bar, and during the completion of its stroke lessens the rapidity of such movement; thereby causing a'diminution of the speed of the valve at a certain predetermined period.

3. The combination with a multiported or gridiron main valve for each end of the cylinder, of multiported or gridiron auxiliary or cut-off valves superimposed upon said main valves, actuating fixed main and governorcontrolled auxiliary eccentrics for said valves, mechanism for connecting each of said valves with its eccentric comprising a rock-shaft, a rocker-arm carried thereby, a radius-bar pivoted to the engine-frame, a link connecting said radius-bar and the valve-rod so as to form a toggle-joint, and a link connecting said rocker-arm with said toggle-joint mechanism, said rocker-arm and toggle mechanism being so positioned and timed relative to each other that the maximum rapidity of movement is imparted the toggle mechanism by the rocker-arm during the first part of the stroke of said rocker-arm, the rapidity of such movement being lessened during the last part of ing a rocker-arm secured thereto, a radiusbar, a link connecting said radius-bar with the valve-rod of the main valve and forming with said radius-bar a toggle-joint mechanism, a link connecting the rocker-arm-on said rock-shaft with said toggle mechanism, said rocker-arm being so timed and positioned relative to the said toggle mechanism as that said lnain valve is given its maximum rapidity of movement during the first part of the stroke of said rocker-arm and a dwell or diminution of speed during the latter part of the rockerarm stroke; a second rock-shaft provided with a rocker-arm, a bell-crank lever connected with said auxiliary valve and a link connecting the last-mentioned rocker-arm with said bell-crank lever, said second rock-shaft being so timed and positioned as to give similar diminution of speed at end of stroke to said auxiliary valve as in caseof the said main Valve.

JAMES ALWARD SEYMOUR.

Witnesses:

WILLIAM H. PENARD, J r., NYDIA SOHUCH. 

